Coding of spatial and temporal frequency in bat biosonar

空间频率的概念在威塞尔和休贝尔的开创性工作中被引入到视觉大脑研究中，这有助于理解大脑如何处理物体的外围表征。许多研究表明，生物声纳系统可以很好地取代或补充视觉对象感知，但尽管回声定位蝙蝠的空间频率具有直接的生态学相关性，但这一参数在生物声纳中并未受到任何科学关注。在实验室和野外对蝙蝠在水面上捕食的心理物理学研究的基础上，我们将测试蝙蝠可以分析自然水面的空间和时间频率模式的假设，以确定其干扰是可能的猎物。实验计划从两个正式的心理物理检测实验开始，量化感知对空间频率和时间频率的敏感度。在这些基础上，将研究沿空间和时间频率轴的掩蔽，以便对蝙蝠可以检测到的猎物诱导的干扰有多小进行定量估计。这些正式实验与飞行室实验相辅相成，在飞行室内实验中，对生物声纳专家道本顿蝙蝠的狩猎序列进行了评估，在水面上，可以系统地操纵水面的空间和时间频率。这项拟议的研究将首次深入了解生物声纳系统如何解决这些具有挑战性的任务，尽管它缺乏明确的空间排列的传感器阵列和不连续的时间采样。

The concept of spatial frequency, introduced in the pioneering work by Wiesel and Hubel into visual brain research, was instrumental in understanding how peripheral representations of objects are processed by the brain. Many studies have shown how well biosonar systems can replace or complement visual object perception but, despite a direct ecological relevance of spatial frequencies for echolocating bats, this parameter has not received any scientific attention in biosonar. Building upon psychophysical studies of bats hunting above water surfaces, both in the lab and in the field, we will test the hypothesis that bats can analyse both the spatial and temporal frequency patterns of natural water surfaces to identify disruptions thereof as possible prey. The experimental program starts out with two formal psychophysical detection experiments, quantifying perceptual sensitivity to spatial frequency and temporal frequency. On these foundations, masking along the spatial and temporal frequency axes will be investigated allowing for quantitative estimates of how-small prey-induced disruptions may be to be detectable by bats. These formal experiments are complemented with flight-room experiments where hunting sequences of biosonar specialists, Daubentons bats, are evaluated above a water surface where both spatial and temporal frequency of the water surface can be systematically manipulated. The proposed research will provide first insights into how a biosonar system solves these challenging tasks despite its lack of an explicit spatially arranged sensor array and its discontinuous temporal sampling.